1. Field of the Invention
The invention relates to plugs for 115 volt and 230 volt electrical line plugs, and more particularly to an electrical plug having means for temporarily manually locking the plug when plugged into an electrical outlet to prevent accidental disengagement of the plug from the outlet.
2. Description of the Prior Art
Current portable electrical devices in the United States utilize line cords having a plug for attachment to 115 volt and 230 volt outlets. The electrical codes require one wire of the supply lines to an outlet to be grounded at the distribution panel, and a separate grounding lead to be run from the panel to each outlet. To minimize possibilities of electrical shock, current electrical appliances, tools and the like having metal cases, frames, etc. are required to have three-wire cords in which a grounding wire is connected to such metal parts, and a pair of feed wires connected to the electrical device. The pair generally includes a pair of feed wires having a "hot" wire, and a neutral wire which is independent of the grounding wire connected to the metal parts.
The plug that connects to an outlet includes a pair of flat pins connected to the pair of feed wires, and a third, essentially U-shaped, grounding pin connected to the grounding wire. The outlet includes a matching socket for receiving the flat pins and the grounding pin. The grounding socket has an electrical connection to the grounding wire lead from the distribution panel.
Common line cord plugs in present use, when plugged into an outlet, are easily dislodged from the outlet. This problem is especially annoying when using tools and extension cords. A slight pull or strain on the line cord or the extension cord often disconnects the tool. Inconvenience and waste of time results. Thus, there is a need for a line cord plug that may be easily connected to an outlet and manually locked therein, and which can be quickly released when desired.
Prior art attempts at solving this problem include U.S. Pat. No. 4,111,509 to Novak which utilizes a split grounding pin that is expanded after insertion of the plug in an outlet. Hubbel et al., U.S. Pat. No. 2,683,864 teaches a grounding pin having a spring strip at its distal end, and a screw to push the strip against the outlet body. Other related references include U.S. Pat. Nos. 5,082,450; 3,890,025; 3,358,265; and 2,261,615.